[Bug analyzer/110543] New: RFE: Add optional trim of the analyzer diagnostics through system headers.

[Bug analyzer/110543] New: RFE: Add optional trim of the analyzer diagnostics through system headers.

[vultkayn at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110543

            Bug ID: 110543
           Summary: RFE: Add optional trim of the analyzer diagnostics
                    through system headers.
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: analyzer
          Assignee: dmalcolm at gcc dot gnu.org
          Reporter: vultkayn at gcc dot gnu.org
  Target Milestone: ---

See https://godbolt.org/z/sb9dM9Gqa for a reproducer on trunk.

Given an issue on std::shared_ptr<>, the analyzer emits a path that I'd like to
optionally shorten, by trimming it.
Looking at the reproducer, I believe it would be desirable the analyzer emits
similar diagnostics for smart pointers as it is for raw pointers, i.e. the
diagnostic should not dive into the standard library, but rather stop at the
faulting frame.

Thus behaves as follow, _by default_:

<source>: In function 'int main()':
<source>:5:8: warning: dereference of NULL 'a' [CWE-476]
[-Wanalyzer-null-dereference]
    5 |   a->x = 4; /* Diagnostic would path should stop here rather than going
to shared_ptr_base.h */
      |   ~~~~~^~~
  'int main()': events 1-2
    |
    |    4 |   std::shared_ptr<A> a;
    |      |      ^
    |      |      |
    |      |      (1) 'a' is NULL
    |    5 |   a->x = 4; /* Diagnostic path should stop here rather than going
to shared_ptr_base.h */
    |      |   ~~~~~~~~
    |      |        |
    |      |        (2) dereference of NULL 'a'
    | 

A flag akin to -fanalyzer-trim-diagnostic-path=<maxdepth>|std would then be
introduced to do so, with a default value of std.
Such option would be useful for future support of C++, but could be extended to
any "system header", thus also be used in C.


A slight variation would be to trim all but the last exceeding event, so that
the user would still get feedback on template deducted types.

What do you think ?

[Bug analyzer/110543] RFE: Add optional trim of the analyzer diagnostics through system headers.

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110543

--- Comment #1 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The trunk branch has been updated by Benjamin Priour <vultkayn@gcc.gnu.org>:

https://gcc.gnu.org/g:ce8cdf5bcf96a2db6d7b9f656fc9ba58d7942a83

commit r14-3205-gce8cdf5bcf96a2db6d7b9f656fc9ba58d7942a83
Author: benjamin priour <vultkayn@gcc.gnu.org>
Date:   Mon Aug 14 17:36:21 2023 +0200

    analyzer: New option fanalyzer-show-events-in-system-headers [PR110543]

    This patch introduces -fanalyzer-show-events-in-system-headers,
    disabled by default.

    This option reduces the noise of the analyzer emitted diagnostics
    when dealing with system headers.
    The new option only affects the display of the diagnostics,
    but doesn't hinder the actual analysis.

    Given a diagnostics path diving into a system header in the form
    [
      prefix events...,
      system header call,
        system header entry,
        events within system headers...,
      system header return,
      suffix events...
    ]
    then disabling the option (either by default or explicitly)
    will shorten the path into:
    [
      prefix events...,
      system header call,
      system header return,
      suffix events...
    ]

    Signed-off-by: benjamin priour <priour.be@gmail.com>

    gcc/analyzer/ChangeLog:

            PR analyzer/110543
            * analyzer.opt: Add new option.
            * diagnostic-manager.cc
            (diagnostic_manager::prune_path): Call prune_system_headers.
            (prune_frame): New function that deletes all events in a frame.
            (diagnostic_manager::prune_system_headers): New function.
            * diagnostic-manager.h: Add prune_system_headers declaration.

    gcc/ChangeLog:

            PR analyzer/110543
            * doc/invoke.texi: Add documentation of
            fanalyzer-show-events-in-system-headers

    gcc/testsuite/ChangeLog:

            PR analyzer/110543
            *
g++.dg/analyzer/fanalyzer-show-events-in-system-headers-default.C:
            New test.
            * g++.dg/analyzer/fanalyzer-show-events-in-system-headers-no.C:
            New test.
            * g++.dg/analyzer/fanalyzer-show-events-in-system-headers.C:
            New test.

[Bug analyzer/110543] RFE: Add optional trim of the analyzer diagnostics through system headers.

[vultkayn at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110543

Benjamin Priour <vultkayn at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|UNCONFIRMED                 |RESOLVED

--- Comment #2 from Benjamin Priour <vultkayn at gcc dot gnu.org> ---
Fixed by the above patch